Close up of Saturn's clouds, photographed by Voyager 1, 1980.

Saturn is a gas giant with an atmosphere consisting mainly of hydrogen and helium, similar to that of Jupiter. The atmosphere contains banded cloud structures similar to those seen on Jupiter, as well as oval storms such as the dark brown feature towards the top of the photograph. Saturn's bands are fainter than Jupiter's, and are wider nearer the equator. Detail of the cloud tops on Saturn is not visible from Earth, and it was not until the Voyager misions that circulation patterns in the upper atmosphere could be observed. NASA's two Voyager spacecraft were launched in 1977 to explore the planets in the outer solar system. Voyager 1 flew past Saturn at a height of 124,000 kilometres in November 1980, having previously visited Jupiter.